Install script should notify user that file-does-not-exist error on path variable configuration is negligible [fish shell]

While running the command suggested on the ghcup page (curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | sh),
the script asked me:

Detected fish shell on your system...
If you want ghcup to automatically add the required PATH variable to "/home/anselmschueler/.config/fish/config.fish"
answer with YES, otherwise with NO and press ENTER.

After answering "YES", an error appeared proclaiming that the file mentioned did not exist.
However, the script did create the file, but didn't notify me of this.
This is bad. Since the changes in that file take a shell restart to go into effect, I at first assumed the operation had failed completely, and scrambled to obtain the code that was intended to be added to the config file.

I believe there should be a message in this event informing the user that there is no need to worry.